Drug Being Tested To Help Heal Eye Injuries

February 18, 1991|By ESTHER MORGO Staff Writer

NORFOLK — The 10-year-old from North Carolina injured her eye about a week ago when she leapt off a swing in her best friend's yard.

Kimberly Herring landed hands down, on a stick, which popped up and poked her in the eye. She was rushed to an eye specialist on Cape Hatteras, then flown by helicopter to Children's Hospital of the King's Daughters in Norfolk for treatment.

Herring is just one of about 20,000 people in the nation each year who get a hyphema, or bleeding in the chamber of the eye between the iris and the cornea, said Dr. Earl Crouch Jr., chairman of ophthalmology at Eastern Virginia Medical School. Most result from an accident.

She is one of only a dozen participants in clinical tests in Norfolk for a new form of drug to treat these injuries. The drug is designed to avoid severe side effects incurred by 20 percent of patients who took an oral form of the same medication.

Crouch, who in 1976 developed the oral drug to treat hyphemas, said that he remained dissatisfied with the treatment because about 1 in 5 patients had a severe reaction to it.

The new form of the drug, applied directly to the injured portion of the eye, should not cause the same complications because it is not absorbed into the bloodstream, he said.

In Hampton Roads, about 80 patients a year are treated for hyphemas. The injuries are caused by seemingly common accidents, involving anything from a large object, like a fist or rubber ball, or a small speeding missile, like a BB pellet, hitting the eye.

The injury can lead to partial or total blindness in some patients if not treated properly, Crouch said.

The oral drug, aminocaproic acid, was a breakthrough compared to previous treatment, which mainly involved lying in bed with a patch over the eye, hoping the injury would heal, Crouch said.

When patients took the oral drug, they developed a variety of problems including nausea, low blood pressure, and vomiting, which could cause renewed bleeding by dislodging the blood clot which forms as the injury heals.

The second hemorrhage can create blood staining of the cornea, glaucoma, or optic nerve damage, all of which can cause vision loss, Crouch said.

So Crouch set out to develop a topical form of the drug, to be applied directly to the eye, healing the hyphema without being absorbed into the bloodstream.

The prelude to the clinical trials started in 1984, with a collaboration between Crouch and Dr. Patricia Williams, professor of pharmacology at the medical school.

It took more than 6 years of laboratory work on rabbits, chosen over rats because their eye structure is more similar to the human eye, to determine the optimal dosage and method of delivery, Williams said.

``We had to prove that the drug decreased the incidence of rebleeding, without being toxic to the delicate tissue surrounding the eye,'' she said of the topical application.

The research has been funded by the medical school and grants totaling $68,000 from the Lion's Eye Bank and Research Institute of Eastern Virginia.

Crouch and Williams began testing patients nine months ago to compare the two forms of the drug but they were unsure of the results until this month, after getting the results from nine patients, Crouch said.

The clinical trials are ``double-masked,'' meaning that neither the doctors nor patients know whether the patient is receiving the oral or topical treatment, Crouch said.

The medication is controlled by a pharmacist, to avoid scientific bias on the part of doctors who developed the new drug, he said.

Researchers plan to test about 40 patients in Norfolk, and the trials may be expanded to the University of Illinois starting this spring, Crouch said.

So far, Crouch said, the topical gel seems to work as well as the oral drug.

The gel produces few noticeable side effects, except for an initial stinging when the drug is placed in the patient's eye.

Five of the patients were treated with the gel and four got the oral drug, he said.

Long range goals include increasing the duration of action of the drug, which currently lasts for six hours, and developing a medicated shield to place over the eye, the doctors said.